Laser Devices Research Articles

A topological route to engineering robust and bright supersymmetric laser arrays

In recent years, several proposals that leverage principles from condensed matter and high-energy physics for engineering laser arrays have been put forward. The most important among these concepts are topology, which enables the construction of robust zero-mode laser devices, and supersymmetry (SUSY), which holds the potential for achieving phase locking in laser arrays. In this work, we show that the relation between supersymmetric coupled bosonic and fermionic oscillators on one side, and bipartite networks (and hence chiral symmetry) on another side can be exploited together with non-Hermitian engineering for building one- and two-dimensional laser arrays with in-phase synchronization. To demonstrate our strategy, we present a concrete design starting from the celebrated Su-Schrieffer-Heeger (SSH) model to arrive at a SUSY laser structure that enjoys two key advantages over those reported in previous works. Firstly, the design presented here features a near-uniform geometry for both the laser array and supersymmetric reservoir (i.e., the widths and distances between the cavity arrays are almost the same). Secondly, the uniform field distribution in the presented structure leads to a far-field intensity that scales as N2 where N is the number of lasing elements. Taken together, these two features can enable the implementation of higher-power laser arrays that are easy to fabricate, and hence provide a roadmap for pushing the frontier of SUSY laser arrays beyond the proof-of-concept phase.

Characterization of AlGaAs/GeSn heterojunction band alignment via X-ray photoelectron spectroscopy

GeSn-based SWIR lasers featuring imaging, sensing, and communications have gained dynamic development recently. However, the existing SiGeSn/GeSn double heterostructure lacks adequate electron confinement and is insufficient for room temperature lasing. The recently demonstrated semiconductor grafting technique provides a viable approach toward AlGaAs/GeSn p-i-n heterojunctions with better electron confinement and high-quality interfaces, promising for room temperature electrically pumped GeSn laser devices. Therefore, understanding and quantitatively characterizing the band alignment in this grafted heterojunction is crucial. In this study, we explore the band alignment in the grafted monocrystalline Al0.3Ga0.7As /Ge0.853Sn0.147p-i-n heterojunction. We determined the bandgap values of AlGaAs and GeSn to be 1.81 eV and 0.434 eV by photoluminescence measurements, respectively. We further conducted X-ray photoelectron spectroscopy measurements and extracted a valence band offset of −0.25 eV and a conduction band offset of 1.126 eV. A Type-I band alignment was confirmed which effectively confines electrons at the AlGaAs/GeSn interface. This study enhances our understanding of the interfacial band structure in grafted AlGaAs/GeSn heterostructure, providing experimental evidence of the Type-I band alignment between AlGaAs and GeSn, and paving the way for their future application in laser technologies.

Backflow Simulation Combined with Laser Visualization Regarding Dust Removal Effect during Tunnel Construction

The removal of respirable dust and harmful gasses in tunnel construction is a crucial topic for the occupational safety of tunnel construction workers. Mechanical ventilation is the most widely used method to remove the dust at present. But respirable dust is difficult to remove by sedimentation because of the small particle size. The setting of airflow rate in the ventilation duct and the distance between the ventilation duct and the working face highly affect the efficiency of dust removal. When the ventilation duct is far away from the working face, there is often no effective air flow reaching the working face due to the backflow. So, understanding the airflow distribution in the tunnel is necessary to evaluate dust removal effects. This contribution simulates the airflow of the Zentrum am Berg (ZAB) tunnel through numerical simulation and also sets up the laser device to visualize the air flow. The backflow sections from numerical simulation and laser visualization are verified and compared with each other to provide guidance on dust removal effect optimization during tunnel construction.

Multiple-beam output, high-peak power passively Q-switched Nd:YAG/Cr4+:YAG laser for ignition application - Modeling of laser pulse characteristics and thermal behavior

In this work we report on the characteristics of a passively Q-switched Nd:YAG/Cr4+:YAG laser with four beams, developed for studies on the laser ignition of different combustible mixtures. The compact laser contains a Nd:YAG/Cr4+:YAG ceramic composite medium, with a monolithic optical resonator. A configuration in which each beam contains laser pulses with an energy of 3.1 mJ and a duration of 0.9 ns (i.e. with a peak power of 3.4 MW) is discussed; operation can be performed in pulse-burst mode, with up to five pulses per pumping pulse. The characteristics of the laser pulses are described by a model based on the rate equations for the photon flux and population inversions in the Nd:YAG gain medium and in the Cr4+:YAG medium with saturable absorption. In addition, the thermal effects are simulated for the operation up to 100 Hz repetition rate, considering the Nd:YAG/Cr4+:YAG laser medium with two geometries, the first of the rod type and the second of the annular type (i.e. cylinder with a central hole) for a good management of thermal effects. This work is an important advancement towards developing a compact laser device with multiple beams, featuring laser pulses and structural properties suitable for igniting combustible mixtures in real engines.

Effect of gamma-rays irradiation on wettability of sol–gel silica nanofilms

Silica nanofilms are often used as antireflection films due to their unique optical properties. In the national high-power laser systems, in order to reduce optical reflection, the silica films are covered on the final optical components. However, the gamma radiation generated during the operation of these systems alters the properties of the silica films on the optical components. While wettability serves as the cornerstone of dust and pollution prevention in engineering technology, it has garnered limited attention in the research of optical components for high-power laser devices. Hence, this paper delves into the surface wettability and intricate hydrodynamics of droplets on silica films, both before and after gamma ray irradiation. The findings reveal that as the irradiation dose increases, the surface energy of the silica film rises, rendering it more lyophilic. By analyzing the impact dynamics of droplets on the silica thin film, we conclude that gamma irradiation renders the silica film coating on optical element surfaces more susceptible to contamination.

Semiconductor Laser Packaging Technology: Thermal Management, Optical Performance Enhancement and Reliability Studies

This review article presents a comprehensive and in-depth discussion of thermal management, optical performance enhancement, and reliability issues in semiconductor laser packaging technology. By synthesising existing literature and research results, the article presents a systematic summary of the research progress and practical applications of semiconductor laser packaging technology in these key areas. In the section on thermal management, the article reviews different heat sink technologies, packaging structures, and solid crystal materials with the aim of improving the thermal stability and long-term reliability of semiconductor la ser devices. In the section on optical performance enhancement, the article outlines beam shaping techniques and packaging technologies. It also addresses reliability issues in packaging, discussing optical mirror damage as well as stress and mechanical damage. The aim of this review is to provide assistance for the further development and application of semiconductor laser packaging technology, with the objective of promoting the rapid and healthy development of the laser industry.

Does the holmium laser have a place in the treatment of pilonidal cysts? (Pilolas study).

Recently, a minimally invasive procedure based on a laser technique (SiLaT) has been developed for the treatment of pilonidal cysts. Although less invasive and less painful than surgery, this solution is nevertheless limited by its high cost. Other more affordable laser devices, such as the holmium laser, are also used in minimally invasive surgery. The objective of this study was to evaluate the possibility of using the holmium laser instead of the SiLaT laser in the treatment of pilonidal cysts. Retrospective cohort study with the primary endpoint being the cure rate one month after treatment. Median duration of local care was 21days (mean = 22 ± 7.5) and healing rate at 1month was 90.7%. During follow-up, 102 patients (44.9%) experienced pain in the coccygeal region often exacerbated by sitting and significantly more common in people with a small frame, overwhelmingly female. A surgical site infection was reported in 36 patients (15.9%). Recurrence, occurred in 39 patients (17.2%), was related to cyst type (type 1 do not recur, type 3 recur twice three time than type 2). Holmium laser does not differ from SiLaT laser in the healing rate of pilonidal cysts after treatment. However, it is characterised by a moderately higher incidence of complications, foremost of which is the occurrence of pain that can persist for up to a year after the procedure and which could be related to an increase in heat inherent to the use of holmium. As a result, this procedure does not seem to represent an alternative to SiLaT.

Comparative Analysis of Cellulite Treatment Modalities: A Systematic Review.

Cellulite is a highly prevalent and aesthetically distressing skin condition. Whilst there are a variety of treatment modalities, none are definitively established. This systematic review aims to assess invasive and noninvasive treatment modalities for cellulite management. The review protocol was published and registered a priori (PROSPERO CRD42022359334). A comprehensive electronic search for relevant randomised controlled trials, (RCTs) was performed in CENTRAL, MEDLINE, Embase and Web of Science databases. Study quality and risk of bias were assessed using Cochrane's risk of bias tool, respectively. Overall, 753 studies were initially identified, of which 24 randomised controlled trials (RCTs) satisfied the eligibility criteria with a total of 2084 patients with a mean follow-up of 3.33 ± 13.4weeks. Evaluated interventions included mechanical stimulation, topical therapy, shock wave therapy (SWT), laser and light-based devices, radiofrequency therapy, subcutaneous injectables, and ultrasound. SWT emerged as a standout intervention, demonstrating a consistent cellulite reduction score of 2.07 ± 0.39 across four studies. Radiofrequency therapy exhibited a statistically significant reduction of thigh circumference (- 2.09cm, p < 0.001) and subcutaneous tissue thickness (- 2.23cm, p < 0.001). Subcutaneous injectables, specifically collagenase Clostridium histolyticum-aaes, demonstrated a statistically significant improvement in the clinician-reported photonumeric cellulite severity scale (17.0%) and patient-reported photonumeric cellulite severity scale (25.7%) (p < 0.001). The overall quality of the studies using the grading of recommendations, assessment, development and evaluation approach was moderate. This is the first methodologically robust systematic review evaluating interventions for cellulite. SWT, radiofrequency therapy, and subcutaneous injectables have shown promising findings in cellulite treatment. The journal asks authors to assign a level of evidence to each article. For a complete description of Evidence-Based Medicine ratings, see the Table of Contents or the online Instructions for Authors at www.springer.com/00266 .

Single-mode selection in a non-strongly coupled whispering gallery mode cavity

Mode selection through coupling multiple cavities has proven to be an effective method for constructing single-mode lasers. In coupled Fabry–Perot cavities, it is well accepted that mode selection relies on the strong coupling effect of closely contacted component structures. However, in coupled whispering gallery mode (WGM) cavities, the mode-selection mechanism remains under debate due to the inconsistent characteristics of the selected mode. Herein, we elucidate that the inconsistency can be attributed to varied selection mechanisms led by the trade-off between coupling strength and field distortion. Particularly, it is demonstrated that except for a traditional strong-coupling configuration, single-mode selection can also be achieved in an intermediate-coupling WGM configuration, where two component cavities depart from each other. This study addresses the gap in understanding mode selection in WGM cavity structures and explains the varied characteristics of single-mode lasing reported in the literature, thereby offering new insights into the development of miniaturized, low-threshold, single-mode laser devices.

Electric spaser constructed by mechanically-knitted microribbons

The advancement of developing spaser devices operated upon electrical pumping has attracted popular attentions, but suffering from several challenges including rational cavity configuration, nonradiative recombination loss, Joule heating, metallic loss and other aspects. Herein, we experimentally exhibit an electrically-driven spaser device, which is composed of one Ga-doped ZnO (ZnO:Ga) microribbon crossed with another Au nanoparticles-embedded ZnO:Ga (AuNPs@ZnO:Ga) microribbon that are linked through ballistic interconnects. The spaser emits at a wavelength of approximately 550 nm, which could be resulted from light amplification of the sandwiched AuNPs plasmons. Experimental investigation reveals that the AuNPs@ZnO:Ga⊗ZnO:Ga microribbon crossed structure exhibits quasi-Schottky junction characteristics, which allows to energetize the current passing through the crossed area, thus generating hot electrons. While, the smoothness surfaces of the ZnO:Ga microribbons, by combining with the sandwiched AuNPs, enable to construct plasmonic nanocavity (the crossed ZnO:Ga-AuNPs-ZnO:Ga structure). In which the light-emission can be plasmonically confined at the subwavelength scale with the cavity length dominated by the AuNPs semidiameter in average. As the voltages applied onto both the microribbons respectively reaching threshold, the strongly-confined hot electrons in the well-designed ZnO:Ga-AuNPs-ZnO:Ga structure allow the spasing action to be realized, which are plasmonically amplified by AuNPs plasmons. Our results provide an instructive guidance to the realization of plasmonic laser devices upon electrical excitation in future.

In Vivo Imaging Techniques for the Human Scalp: A Systematic Review of the Literature.

Scalp inflammation and alopecia are distressing conditions for which patients regularly present to dermatology. Although some diagnoses can be made clinically, others require biopsy, which carries the risk of pain, infection, bleeding, and scarring. This review examines the existing literature regarding noninvasive in vivo imaging techniques and their evidence and utility in evaluating scalp pathology, with a focus on the diagnostics of hair conditions. A systematic literature search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines without timeframe restrictions. The PubMed and Clarivate (Web of Science) databases were searched using the terms ("imaging" OR "in-vivo imaging" OR "non-invasive imaging" OR "non-invasive in vivo imaging" "imaging," "in-vivo imaging) AND ("human scalp disorders" OR "scalp" OR "hair loss" OR "alopecia"). Peer-reviewed randomized control trials (RCTs), prospective studies, retrospective studies, and case series or reports discussing in vivo imaging of the scalp published before 2022 were selected. Forty-two studies were included and discussed; modalities included laser devices (n = 27), ultrasound (US) (n = 13), infrared thermography (n = 1), skin capacitance imaging (SCI), and ultraviolet light-enhanced visualization (ULEV) (n = 1). The most common laser devices used were reflectance confocal microscopy (RCM), multiphoton microscopy (MPM), and optical coherence tomography (OCT). US techniques included high-frequency US (HFUS) and US biomicroscopy (UBM). Quality imaging of the scalp in the setting of alopecic, neoplastic, and inflammatory diseases is highly sought after. Many of these noninvasive imaging techniques show promise, each with individual advantages and disadvantages in imaging-specific conditions. Ultimately, noninvasive imaging techniques may be used to optimize patient management and minimize morbidity associated with scalp biopsies.

Efficacy and Safety of Laser Therapy and Phototherapy in Cicatricial and NonCicatricial Alopecia: A Systematic Review Study.

In recent years, the application of various light and laser devices in the treatment of different types of alopecia has been established. This systematic review aims to assess the efficacy and safety of laser therapy and phototherapy in cicatricial and non-cicatricial alopecia. A comprehensive search was conducted on PubMed, Scopus, Science Direct, and Google Scholar. Articles were evaluated across four subgroups: alopecia areata, androgenic alopecia, telogen effluvium, and cicatricial alopecia. Included studies were published in English or Persian between January 2010 and September 2023, focusing on interventional, cohort, or case series research that achieved a minimum score of 75% on the EBL checklist. Exclusion criteria encompassed animal and in vitro studies, review articles, case reports, duplicated or irrelevant research, as well as studies that did not meet the designated EBL score. Editorial letters and case studies were also excluded. Initially, 965 records were collected, resulting in the inclusion of 58 studies in the final review: 26 on alopecia areata, 26 on androgenic alopecia, five on cicatricial alopecia, and one on telogen effluvium. Narrow-band ultraviolet B, 308-nm excimer laser, and psoralen ultraviolet A therapy showed varying effectiveness; specifically, the excimer laser was notably effective for patients with shorter disease duration. In androgenic alopecia, erbium-glass and thulium lasers effectively increased hair density but showed a gradual decline posttreatment. Low-level light/laser therapy also increased hair density and diameter and exhibited potential benefits when used alongside minoxidil, but did not significantly enhance outcomes in telogen effluvium treatment. Light/laser therapy can serve as an additive treatment for cicatricial alopecia, particularly lichen planopilaris, but has limited efficacy in treating telogen effluvium. Overall, light/laser therapies exhibit a significant positive effect on increasing hair density and diameter across various alopecia types.

Concurrent Validity and Interunit Reliability of 25-Hz GNSS Units for Profiling Sprinting Performance.

Dennison, L, Duthie, GM, Ehrmann, F, and Psarakis, MA. Concurrent validity and interunit reliability of 25-Hz GNSS units for profiling sprinting performance. J Strength Cond Res XX(X): 000-000, 2024-Profiling sprint performance by assessing within-race velocity or time is crucial for understanding an athlete's capabilities and identifying areas for improvement. While traditional gold standard systems provide valid and reliable measurements, they are often costly, laboratory-based, or impractical for field-based settings. New Global Navigation Satellite System (GNSS) units (25 Hz) with higher sampling rates may address some of these limitations. The purpose of the project was to evaluate the concurrent validity and interunit reliability of 25-Hz GNSS units by examining their agreement with laser devices and timing gates for velocity measurements and sprint/interval times. Concurrent validity was assessed during a real track and field training session. Thirty subjects each completed 3 to 6 maximal 40-meter sprints, for a total of 106 sprints, while being assessed simultaneously through all systems. Interunit reliability was assessed by placing 3 GNSS units on a motor vehicle and completing 60 accelerations from 0 to 60 m. Low mean bias (<1%) and typical error less than <2% for all measurements demonstrate excellent agreement between GNSS and criterion devices. The units demonstrated good reliability for the 0-10 m interval time (intraclass correlation coefficient [ICC] = 0.86), excellent reliability for all remaining 10 m to 60 m intervals (ICC = 0.91-0.99), sprint times 0-60 m (ICC = 0.97), and maximal sprint velocity (ICC = 1.0). These GNSS units provide an efficient and feasible alternative to traditional measurement devices. For coaches, this technology offers a scalable method to concurrently assess the sprint performances of multiple athletes during training and competitions, enabling evidence-based decisions to guide athletic development.

Effectiveness of Activated Sodium Hypochlorite Irrigation by Shock Wave-Enhanced Emission Photoacoustic Streaming, Sonic and Ultrasonic Devices in Removing Enterococcus faecalis Biofilm From Root Canal System.

Aim: To compare shock wave-enhanced emission photoacoustic streaming (SWEEPS) with sonic- and ultrasonically activated irrigation systems in removing Enterococcus faecalis biofilm from the root canal system. Methodology: Fifty human single-canalled mandibular premolars were included in the study. After access cavity preparation, the root canals were prepared to a standardized size and taper. Then, the entire root surface was covered with two layers of resin, and the root apices were sealed before sterilization. All root canals were inoculated with E. faecalis biofilm, and the samples were incubated aerobically for 2 weeks at 37 °C. Biofilm formation was confirmed by scanning electron microscopy. All samples were randomly divided into five groups (n = 10 each) based on their irrigation activation method as A (no treatment or negative control), B (no irrigation or positive control), C (sonically activated irrigation (SAI)), D (ultrasonically activated irrigation (UAI)), and E (needle irrigation activated by an Er: YAG laser device using a SWEEPS quartz tip (SWEEPS)). Then, dentine chips were retrieved, vortexed, and diluted for colony-forming unit counts. Data were analysed using analysis of variance and post-hoc Tukey tests (α = 5%). Results: All methods could significantly reduce E. faecalis biofilm compared with control so that the UAI, SWEEPS, and SAI groups indicated a 23.54%, 14.89%, and 7.81% biofilm reduction, respectively. UAI demonstrated a significantly more effective reduction of E. faecalis biofilm than SAI (p = 0.004). Conclusions: All irrigation activation methods significantly reduced E. faecalis biofilm, with ultrasonic use being the most effective.

Directional growth and composition design of the highly disordered Yb3+ doped Ca(Gd1-xLux)AlO4 crystals for ultrafast lasers

The unique disordered structure of the CaGdAlO4 crystal, combined with its exceptional thermal and spectral properties, has contributed to its growing popularity in the field of ultrafast lasers. In this work, high quality Yb3+ doped CaGdAlO4 crystals were directionally grown by the rapid and cost-effective micro-pulling down method for the first time. The anisotropic analysis determined [100]-orientation as the optimal growth direction due to its superior spectral, thermal and continuous-wave laser properties compared to that of [001]-orientation. Based on the optimized [100]-orientation, two novel crystals, Yb3+:CaGd1-xLuxAlO4 (x = 0.05 and 0.1), were designed by incorporating Lu3+ into Gd3+ site. Benefiting from the enhanced structure disorder induced by Lu3+ co-doping, the Yb3+:CaGd1-xLuxAlO4 crystals demonstrated superior spectral and pulsed laser performance compared to that of Yb3+:CaGdAlO4, featuring a broader emission spectrum, narrower pulse duration and higher peak power. The utilization of anisotropy and composition design strategies effectively enhanced the spectral and pulsed laser properties, providing a feasible way for the optimization of compact and high-performance laser devices.

Achievement of ductile-regime removal in fabricating Gaussian curved microstructure processed by micro ball-end milling on soft-brittle KDP surface

Laser-induced damage points (known as defects) would seriously reduce the service life of large-aperture KDP optics in high-power laser devices. The ball-end milling procedure is recognized as an efficient method for creating a Gaussian mitigation pit (GMP) to restore the optical transmission performance of functional KDP crystals by removing defects. Nevertheless, achieving smooth and flawless Gaussian curved microstructures is a massive challenge for soft-brittle KDP crystals. Herein, a judging criterion of the ductile-regime machining for the GMP is developed by the models of uncut chip thickness (UCT) and critical milling depth. Simultaneously, the obtained judging criterion can be validated by the microstructure fabrication experiments. Besides, considering the spindle vibration, plowing effect, and machined surface texture, the influence of spindle speed (n), feed rate (f), and tool mark interval (d) on the surface formation mechanism of the GMP is analyzed, respectively. It can be discovered that the n of up to 60,000 r/min can lead to severe velocity fluctuation of the motion system, increasing the UCT and causing brittle fractures on the KDP surface. A low f can result in an undesirable plowing phenomenon, and a large number of crystal materials are accumulated in the up-cut process. Once the f reaches 72 mm/min, the tool path would fluctuate significantly, resulting in poor GMP surface texture. When the d exceeds 15 μm, the surface quality of the GMP can no longer meet the engineering requirements of the Ra ≤ 50 nm. Moreover, the optimized processing parameters of the microstructure fabrication are 47,800 r/min in the n, 30 mm/min in the f, and 5 μm in the d. This study can provide crucial guidance for obtaining the ultra-smooth and defect-free GMP processed in the ductile regime, which would resultantly possess significant theoretical importance and practical value in enhancing the optical properties of flawed KDP crystals.

Vaginal erbium laser versus pelvic floor exercises for the treatment of pelvic organ prolapse: A randomised controlled trial

ObjectivesTo compare the efficacy of Er:YAG laser for mild to moderate pelvic organ prolapse (POP) to that of pelvic floor exercises (PFE). DesignSingle center randomised controlled trial. SettingTertiary center, Belgium. ParticipantsForty-six women with mild to moderate prolapse were enrolled (23 in each group). There were no missing data for the primary outcome; three patients were lost to follow-up at 24-months. InterventionsComparison of vaginal laser treatment (3–6 applications) to PFE (9–18 sessions). Main outcome measuresSubjective change in prolapse symptoms at four months from baseline measured by the Pelvic Organ Prolapse Distress Inventory-6 (POPDI-6) (primary), adverse events, other subjective outcomes and independent anatomical assessment up to 24 months. ResultsThe mean difference in POPDI-6 scores at 4 months was 1.09 (95 %CI = −6.02;8.12), showing non-inferiority of laser to PFE (p = 0.004). Within groups, the difference in mean POPDI-6 four months following the start of therapy tended to be lower for laser-treatment (65.2 % (15/23) of laser-participants were ‘better’ or ‘much better’) than for PFE (60.9 % (14/23) in the PFE group), yet without difference between groups (OR = 1.21; 95 %CI = 0.39–3.23). There were no obvious between group differences in any other subjective nor objective outcomes. At 24 months, 50 % (11/22) of laser-patients and 43 % (9/21) of PFE-patients requested additional, yet alternative treatment. There were no serious adverse events at any time-point. ConclusionsVaginal laser application and PFE improve symptoms of mild and moderate prolapse to a similar extent. Both treatments had a measurable yet not durable effect. There were no adverse events in either arm. Trial registrationClinicalTrials.gov(NCT04523298). FundingThe laser device was provided by Fotona, Slovenia for the duration of this trial.

A Single-Center, Open-Label, Prospective Study of a 589/1319 nm Dual Wavelength Laser for the Treatment of Facial Hyperpigmentation.

Facial hyperpigmentation, characterized by the excessive production of melanin in the skin, is a prevalent dermatological concern affecting individuals of various ethnic backgrounds. To evaluate the safety and efficacy of a multi-wavelength 589/1319 nm dual-pulse duration laser device for the treatment of hyperpigmentation Patients/Methods: A total of 17 healthy women (mean [SD] age of 43.4 [11.6] with skin phototype II-IV) were enrolled in this prospective, single-center study. Eligible participants received up to 3 treatments spaced 3 to 5 weeks apart with 2 follow-up visits at 4 and 12 weeks after the final treatment. Assessments included investigator ratings of skin quality, global aesthetic improvement, and hyperpigmentation. Safety and tolerability were monitored throughout the study. Significant improvements in hyperpigmentation and skin quality were observed at the 2 follow-up visits from baseline in most patients per investigator assessments. Patient satisfaction was high, and treatments were safe with transient self-resolving side effects such as erythema. Laser treatments using a dual-wavelength 589/1319nm device significantly improve facial hyperpigmentation in patients of various skin types. J Drugs Dermatol. 2024;23(11):943-947. doi:10.36849/JDD.8196.

Photobiomodulation therapy to prevent oral mucositis and functional impairment in adult patients with haematological cancer undergoing haematopoietic stem cell transplantation: randomised trial protocol

IntroductionOral mucositis is a highly prevalent condition in individuals treated for haematological neoplasms, primarily during haematopoietic stem cell transplantation (HSCT). The condition is known to delay recovery processes, increasing the...

Correlating stroke risk with non-invasive cerebrovascular perfusion dynamics using a portable speckle contrast optical spectroscopy laser device.

Stroke poses a significant global health threat, with millions affected annually, leading to substantial morbidity and mortality. Current stroke risk assessment for the general population relies on markers such as demographics, blood tests, and comorbidities. A minimally invasive, clinically scalable, and cost-effective way to directly measure cerebral blood flow presents an opportunity. This opportunity has the potential to positively impact effective stroke risk assessment prevention and intervention. Physiological changes in the cerebrovascular system, particularly in response to hypercapnia and hypoxia during voluntary breath-holding can offer insights into stroke risk assessment. However, existing methods for measuring cerebral perfusion reserves, such as blood flow and blood volume changes, are limited by either invasiveness or impracticality. Herein we propose a non-invasive transcranial approach using speckle contrast optical spectroscopy (SCOS) to non-invasively monitor regional changes in brain blood flow and volume during breath-holding. Our study, conducted on 50 individuals classified into two groups (low-risk and higher-risk for stroke), shows significant differences in blood dynamic changes during breath-holding between the two groups, providing physiological insights for stroke risk assessment using a non-invasive quantification paradigm. Given its cost-effectiveness, scalability, portability, and simplicity, this laser-centric tool has significant potential for early diagnosis and treatment of stroke in the general population.